Research Themes and Trends in Ten Top-Ranked Nephrology Journals: A Text Mining Analysis.

BACKGROUND: Nephrology research is expanding, and harnessing the much-needed information and data for the practice of evidence-based medicine is becoming more challenging. In this study, we used the natural language processing and text mining approach to mitigate some of these challenges. METHODS: We analyzed 17,412 abstracts from the top-10 nephrology journals over 10 years (2007-2017) by using latent semantic analysis and topic analysis. RESULTS: The analyses revealed 10 distinct topics (T) for nephrology research ranging from basic science studies, using animal modeling (T-1), to dialysis vascular access-related issues -(T-10). The trend analyses indicated that while the majority of topics stayed relatively stable, some of the research topics experienced increasing popularity over time such as studies focusing on mortality and survival (T-4) and Patient-related Outcomes and Perspectives of Clinicians (T-5). However, some research topics such as studies focusing on animal modeling (T-1), predictors of acute kidney injury, and dialysis access (T-10) exhibited a downward trend. CONCLUSION: Stakeholders of nephrology research may use these trends further to develop priorities and enrich the research agenda for the future.

Bariatric surgery is associated with renal function improvement.

INTRODUCTION: Weight loss after bariatric surgery improves both blood pressure and glycemic control following surgery. The effect of bariatric surgery on renal function is not well characterized. In this study, we sought to quantify the change in renal function over time following surgery. METHODS: We retrospectively reviewed all patients who underwent laparoscopic Roux-en-Y gastric bypass (LRYGB) or laparoscopic sleeve gastrectomy (LSG) between 2012 and 2014 at our institution. The glomerular filtration rate (GFR, mL/min) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Body mass index (BMI, kg/m2) and percent weight loss (%WL) were calculated following the surgery. RESULTS: A total of 149 patients who underwent bariatric surgery were included in this study: LRYGB (n = 86 and LSG (n = 63). In LRYGB group, baseline BMI (kg/m2, ±SD) and GFR (mL/min, ±SD) were 48.5 ± 6.8 and 94.7 ± 23.8, respectively. In comparison, BMI and GFR were 49.1 ± 11.9 kg/m2 and 93.1 ± 28.0 mL/min in the LSG group, respectively. Over the follow-up period (19.89 ± 10.93 months), the patients who underwent LRGYB lost a larger percentage of weight as compared to those in the LSG group (29.9 ± 11.7% vs 22.3 ± 10.7%; p = <0.0001). Overall, GFR improved in both LRYGB (101.0 ± 25.8 mL/min) and LSG groups (97.9 ± 25.8 mL/min) and was not significantly different between the two groups. Of patients with a GFR < 90 mL/min prior to weight loss surgery (n = 62), 42% had improvement of their GFR to > 90 mL/min postoperatively (p < 0.001). There was no relationship between weight loss percentage and GFR improvement (p = 0.8703). CONCLUSIONS: Bariatric surgery was associated with improvement in postoperative renal function at almost two years following surgery but was not different for LRYGB versus LSG. The gain in GFR was independent of percentage of weight lost suggesting an alternate mechanism in the improvement of renal function other than weight loss alone.

Catheter-based therapy for traumatic pseudoaneurysm of the anterior tibial artery.

Tibial artery pseudoaneurysms often result from penetrating or blunt trauma to the lower extremities, or after orthopedic and endovascular interventions. Clinically, these lesions manifest as an expanding pulsatile mass of the affected area accompanied with pain and erythema. Despite the rare occurrence, traumatic tibial pseudoaneurysms can be associated with significant morbidity including local discomfort, rupture, and lower limb ischemia. Duplex ultrasound is considered the gold standard for diagnosis. Treatment options include surgical repair, ultrasound-guided compression or thrombin injection, and endovascular repair. In this report, we describe a 42-year-old male who presented to our center with pulsatile swelling over the mid-lateral aspect of the left leg. The diagnosis of a large anterior tibial artery pseudoaneurysm was made on clinical basis and was confirmed with computed tomography angiography. The lesion was treated endovascularly with a covered stent graft. In conclusion, this case highlights the role of endovascular therapy as a surgery-sparing and minimally invasive approach in managing traumatic peripheral arterial pseudoaneurysms with excellent clinical outcomes.

Fatal superior vena cava rupture complicating dialysis catheter exchange.

Central vein stenosis (CVS) is a common and challenging complication in hemodialysis patients with chronic central venous catheters (CVCs). CVS often remains asymptomatic and is discovered incidentally during follow-up imaging. CVS symptoms include arm swelling, venous hypertension, impaired dialysis flow rates, and development of collateral veins. However, these symptoms can be nonspecific and overlap with other conditions, making the diagnosis challenging. Timely recognition and appropriate intervention are crucial to prevent complications and optimize patient outcomes. Diagnostic tools commonly used include duplex ultrasonography and venography to assess the degree and location of stenosis. Management strategies for CVS encompass a multidisciplinary approach involving nephrologists, interventional radiologists, and vascular surgeons. Initial conservative measures may include anticoagulation therapy, along with pharmacological interventions such as antiplatelet agents and thrombolytics. The endovascular approach is the first line for managing CVS by using balloon angioplasty either alone or in combination with stent placement, but CVS typically recurs frequently, requiring repeated interventions with an increased risk of complications. Additionally, alternative vascular access options such as arteriovenous fistulas or grafts may be considered. In this report, we describe a case of a 25-year-old woman who presented with an extensive history of multiple dialysis access failure for left internal jugular vein central venous tunneled catheter exchange. The procedure was complicated by a fatal superior vena cava rupture likely related to the dislodgment of the guidewire causing perforation into the pericardium space with subsequent cardiopulmonary collapse. The post-mortem autopsy showed severe organized stenosis of SVC and transmural defect above the SVC/atrial junction.

Surgical management of cephalic arch occlusive lesions: are there predictors for outcomes?

Cephalic arch lesions are common cause for dysfunction of brachiocephalic arteriovenous fistulas. For lesions resistant or not amenable to endovascular interventions, we used a term "cephalic arch occlusive lesions" (CAO) that included cephalic arch total occlusion, frequently recurrent stenosis (requiring angioplasty in <3-month intervals), high-grade elastic stenosis (residual stenosis >50% after angioplasty), or other lesions not amenable to endovascular interventions. Herein, we report 40 patients who underwent surgical revisions for total occlusions (17/40), frequently recurrent stenosis (17/40), high-grade elastic stenosis (5/40), and zigzag stenosis (1/40). The revisions included cephalic transposition and venovenostomy (CTV = 37/40), basilic transposition and venovenostomy (1/40), stenotic segment resection (1/40), and cephalic-jugular vein bypass graft (1/40). At 12-month post-CTV, the primary patency of the transposed cephalic vein, the fistula assisted primary and secondary patency rates were 25%, 82% and 97%, respectively. Notably, pre-CTV angioplasty of the proximal cephalic vein was the only significant predictor for the low primary patency rate (hazard ratio 4.5, p = 0.002). Accordingly, the primary patency rates were 12% and 58% in patients with and without pre-CTV angioplasty, respectively. In summary, surgical interventions are effective in salvaging fistulas complicated with CAO. Importantly, pre-CTV angioplasty of the proximal cephalic vein might adversely affect the outcome of CTV.

Dilator-assisted banding for managing complications associated with excessive hemodialysis access flow.

Excessive hemodialysis access flow can be associated with serious complications, such as ischemic steal syndrome and heart failure. Among the therapeutic approaches, endoluminal balloon-guided banding has the advantage of being minimally invasive. However, it requires fluoroscopic guidance. We here report a simpler approach, Dilator-assisted Banding (DAB), in which over-the-wire vascular dilators of known diameters are used as endoluminal-guides to achieve precision banding with or without fluoroscopic guidance. The dilators used are 10, 12, and 14 French, corresponding to 3.3, 4.0, and 4.7 mm in diameter, respectively. Of the seven treated patients with ischemic steal syndrome, three were males, mean age was 67.7 ± 16.3 years, five were diabetics, all were hypertensive, five had fistulas, and two had grafts. Mean age of hemodialysis accesses was 17.2 ± 8.4 months. Three patients had banding without fluoroscopic guidance, including two performed during fistula vein superficialization and basilic vein transposition. With follow-up of 2-12 months, all hemodialysis accesses remained functional. Six patients had complete resolution and one reported marked improvement of ischemic symptoms. In summary, DAB is a simple, effective, and economical flow-reduction alternative for managing ischemic steal syndrome and potentially other complications associated with excessive access flows. In addition, it can be safely performed without fluoroscopic guidance.

The role of stents in hemodialysis vascular access.

Vascular access is the Achilles' heel of dialysis therapy among patient with end stage kidney disease. The development of neointimal hyperplasia and subsequent stenosis is common in vascular access and is associated with significant morbidity. Percutaneous transluminal angioplasty using balloon inflation was the standard therapy of these lesions. However, the balloon-based approaches were associated with poor vascular access patency rate necessitating new inventions. It is within this context that different types of stents were developed in order to improve the overall dialysis vascular access functionality. In this article, we review the available literature regarding the use of stents in treating dialysis vascular access stenotic lesions. Further, we review the major clinical trials of stent use in different anatomic locations and in different clinical scenarios.

Pickering syndrome in a patient with a single kidney: role of renal artery stenting.

Renal artery stenosis (RAS) is associated with hypertension and high mortality rates. With its prevalence and associated risk of death, it is important to screen for patients displaying symptoms of RAS. RAS has a wide spectrum of clinical manifestations and is usually resistant to medical therapy. Of these clinical manifestations is Pickering syndrome which is characterized by bilateral renal arterial occlusion inflow lesions, flash pulmonary edema, acute kidney injury, and hypertensive emergencies in the setting of a preserved left ventricle function. Stenting techniques have been used extensively to treat symptomatic renal artery stenosis with excellent primary patency rate, however have failed to demonstrate a long-term benefit over the optimal medical management alone in randomized trials. However, accumulating evidence suggests that stenting is justified in specific patient subgroups that have severe occlusive renal artery stenoses with significant clinical sequelae, including flash pulmonary edema, acute ischemic kidney injury, and uncontrolled hypertension. In this report we discuss the case of a 32-year-old male who presented to our center with recurrent flash pulmonary edema and hypertensive emergency and was found to have RAS, which responded well to renal artery stenting. In conclusion, correcting the renal arterial inflow stenosis is beneficial and warranted in selective clinical scenarios.

PICC line management among patients with chronic kidney disease.

More than 1 million peripherally inserted central catheters (PICC) are placed annually in the US and are used to provide convenient vascular access for a variety of reasons including long term antibiotic treatment, chemotherapy, parenteral nutrition, and blood draws. Although they are relatively easy to place and inexpensive, PICC line use is associated with many complications such as phlebitis/thrombophlebitis, venous thrombosis, catheter-related infection, wound infection, and central vein stenosis. These complications are far more deleterious for patients with chronic kidney disease (CKD) whose lives depend on a functioning hemodialysis access once they reach end stage kidney disease (ESKD). Despite recent guidelines to avoid PICC lines in CKD and ESKD patients, clinical use remains high. There is an ongoing urgency to educate and inform health care providers and the CKD patients themselves in preserving their venous real estate. In this article, we review AV access and PICC line background, complications associated with PICC lines in the CKD population, and recommendations for alternatives to placing a PICC line in this vulnerable patient population.

Partial aneurysmectomy is effective in managing aneurysm-associated complications of arteriovenous fistulae for hemodialysis: case series and literature review.

Fistula aneurysms are commonly seen and usually do not affect fistula function for hemodialysis. However, these aneurysms are associated with complications that increase the risk of fistula bleeding and loss. The common feature of these complications is that the diseased tissues usually affect a localized area of an aneurysm. Accordingly, we developed a targeted intervention "partial aneurysmectomy" in which only the diseased area was resected. In this report, we sought to examine the outcomes of partial aneurysmectomies performed in 36 cases for the following indications: active bleeding (14%), skin scab plus fistula defect in imminent danger of bleeding (33%), skin necrosis and erosion (28%), and thin-walled aneurysm in danger of rupture (25%). Postoperatively, all patients continued hemodialysis using their fistulae. During 2-18-month follow-up, all fistulae but one were functional and required no intervention on the repaired areas. At 6 months, the aneurysm primary patency, fistula primary patency, and fistula-assisted primary patency rates were 97%, 56%, and 97%, respectively. In conclusion, partial aneurysmectomy is a simple and effective intervention for managing aneurysm-associated complications and preserving fistula function. Owing to its advantages over other interventions, we recommend partial aneurysmectomy as first-line choice for managing aneurysm-associated complications.

Painless myocardial ischemia is associated with mortality in patients with chronic kidney disease.

BACKGROUND: Painless myocardial ischemia (PMI) is associated with poor outcomes in the general population. We hypothesized that the presence of PMI is inversely related to the level of kidney function and is associated with impaired survival in chronic kidney disease (CKD). METHODS: A total of 356 patients who underwent percutaneous coronary intervention were assessed for PMI, which was defined as the absence of chest pain in response to balloon dilation of the affected vessel. Cox proportional hazards analysis was used to calculate 10-year all-cause mortality. RESULTS: There was an increase in PMI occurrence by strata of estimated glomerular filtration rate (eGFR), whereby PMI was present in only 20.6% of individuals with eGFR ≥ 90 ml/min/1.73 m(2), but was found in 50.0% of individuals with eGFR <30 ml/min/1.73 m(2) (p = 0.004 for trend). Classification of individuals as having either CKD or PMI showed significant differences in adjusted mortality between groups (p < 0.001 for trend), with individuals having both CKD and PMI demonstrating the highest 10-year mortality. Compared to individuals with neither CKD nor PMI, individuals with CKD and no PMI had a hazard ratio (HR) for mortality of 1.64 (95% CI: 1.03-2.63, p = 0.038), while individuals with both PMI and CKD had an HR of 2.08 (1.30-3.33, p = 0.002). CONCLUSION: PMI is common in the CKD population, is inversely related to the level of eGFR, and confers a substantially increased risk in CKD. These findings may partially explain the high mortality traditionally attributed to cardiovascular disease in CKD patients.

Chest wall arteriovenous graft for dialysis: A case report.

Upper extremity access sites are the preferred access sites for hemodialysis. With the improvement of the survival in dialysis population, most patients outlive the dialysis access lifespan. As such, some patients exhaust the vascular access options of the upper extremities, which necessitates the search for new access sites. While lower extremity grafts and hemodialysis reliable outflow devices are potential alternatives, these access sites are plagued with recurrent lesions at the venous anastomosis and subsequent thrombosis leading to poor access survival. Within this framework, the axillary-based dialysis access was developed to address these challenges. In this report, we describe a 70-year-old woman who exhausted her upper extremity access sites and eventually underwent a chest wall arteriovenous graft (AVG) that connected the right axillary artery to the right axillary vein. This chest wall AVG remained functional without any intervention for more than 3 years. In conclusion, chest wall AVG access can be a viable option for hemodialysis patients who have exhausted the access sites of the upper extremities, while potentially minimizing complications seen in other methods of vascular access.

Inferior epigastric artery injury after percutaneous imaging-guided peritoneal dialysis catheter placement.

Inferior epigastric artery (IEA) injury is a rare clinical entity that is usually associated with abdominal wall procedures and injuries though can also be spontaneous, particularly in individuals with coagulopathy. Of all described mechanisms of injury, percutaneous peritoneal dialysis (PD) catheter insertion is a rarely encountered, particularly in instances where insertion is performed under imaging guidance. While this injury is self-limited, it can be associated with hemodynamic instability and acute blood loss anemia, which can be fatal if left untreated. Computed tomographic (CT) angiography is the diagnostic method of choice. Transcatheter arterial embolization is an effective treatment modality with a high success rate. Here, we describe a 41-year-old female who underwent percutaneous PD catheter insertion that, despite intraprocedural imaging guidance, was complicated by large hemoperitoneum and clinical instability. Prompt identification of IEA injury followed by immediate intervention with coil embolization led to a successful outcome for this patient in the setting of a life-threatening uncommon complication of such procedure. The details of the diagnostic evaluation and management are outlined.

Loop arteriovenous graft of the chest wall as a viable option for dialysis.

The search for a reliable, complication-free vascular access is crucial among dialysis patients. The creation of a long-term access site for hemodialysis is dependent on several factors that mandate forming a life-plan for dialysis access, with upper extremity vascular access being the preferred route. However, complications including poor maturation, venous anastomosis lesions, and thrombosis are all associated with poor survival of these accesses. As a result, numerous patients within the dialysis population have exhausted access sites in the upper and lower extremities, requiring the search for other access options including chest wall arteriovenous graft (AVG). However, limited data is available about the outcomes of these chest wall grafts. Here, we describe two 62-year-old female dialysis patients who exhausted other dialysis access sites and subsequently underwent arteriovenous loop graft of the chest wall that connected the axillary artery with the ipsilateral axillary vein. These AVGs remained functional during the follow up period. This report highlights the viability of chest wall AVG access in the unique subset of hemodialysis patients who exhausted all other access sites.

Complications of Percutaneous Peritoneal Dialysis Catheter.

A functional peritoneal dialysis (PD) catheter is the cornerstone for the success of renal replacement therapy. This success is largely dependent on adhering to best practices during catheter insertion, which starts with a comprehensive preoperative evaluation that helps in determining the catheter configuration type and both entry and exit sites. Additionally, following the best practice guidelines during PD catheter insertion minimizes undesirable complications and provides a durable functional access for dialysis. However, adverse complications are still encountered despite abiding with these clinical guidelines. These complications are categorized into mechanical and infectious groups. The description and management of these adverse events are discussed in detail in this article with particular attention to the technical pitfalls that can occur during catheter insertion. Avoiding these pitfalls can minimize PD catheter complications and potentially improve clinical outcomes.

Hemodialysis Catheters: Update on Types, Outcomes, Designs and Complications.

Hemodialysis catheters (HDCs) are an essential part of kidney replacement therapy. While these catheters are considered only the bridge to long-term vascular access such as arteriovenous fistulas and grafts, they are associated with significant morbidity and mortality and subsequent increased health care expenditures. However, despite these risks, a large proportion of end stage kidney disease population initiates dialysis using these catheters. The pathogenicity of HDCs stems from its invasive nature to the venous vasculature tree resulting in both mechanical and infectious complications. Therefore, the wide use these catheters in dialysis population and the associated complications necessitated continuous innovations in the catheter material, design, and placement techniques. This review provides an update on the catheter types, catheter tip designs, and the new technologies and innovations aimed to improve the catheter functionality and mitigate its related complications.

Delayed diagnosis of a retained guidewire after bedside femoral venous catheter insertion: A preventable complication.

Central venous catheter (CVC) insertion is a commonly performed procedure that is used for continuous invasive hemodynamic monitoring, fluid resuscitation, drug therapy, and hemodialysis. CVC placement can be associated with serious complications that are mostly preventable. One of these complications is the loss of the guidewire within the intravascular space, which carries a high morbidity and mortality. Here, we describe a 44-year old patient who presented with acute kidney injury and metabolic derangements that necessitated bedside right femoral dialysis catheter to initiate emergent renal replacement therapy. A day after the catheter insertion, the guidewire was noted on a routine chest X-ray extending into the base of the skull. The clinical course was complicated with cerebral infarction. Subsequently, the retained guidewire was removed a few days after the CVC insertion. In summary, the retained guidewire within the circulation is associated with potentially life-threatening and hazardous outcomes. Continuing education, vigilant supervision, and implementing certain protocols are likely to prevent such undesirable events.

Endovascular Management of Thrombosed Dialysis Vascular Circuits.

A functional hemodialysis vascular access is the lifeline for patients with end-stage kidney disease and is considered a major determinant of survival and quality of life in this patient population. Hemodialysis therapy can be performed via arteriovenous fistulas, arteriovenous grafts, and central venous catheters (CVCs). Following dialysis vascular access creation, the interplay between several pathologic mechanisms can lead to vascular luminal obstruction due to neointimal hyperplasia with subsequent stenosis, stasis, and eventually access thrombosis. Restoration of the blood flow in the vascular access circuit via thrombectomy is crucial to avoid the use of CVCs and to prolong the life span of the vascular access conduits. The fundamental principles of thrombectomy center around removing the thrombus from the thrombosed access and treating the underlying culprit vascular stenosis. Several endovascular devices have been utilized to perform mechanical thrombectomy and have shown comparable outcomes. Standard angioplasty balloons remain the cornerstone for the treatment of stenotic vascular lesions. The utility of drug-coated balloons in dialysis vascular access remains unsettled due to conflicting results from randomized clinical trials. Stent grafts are used to treat resistant and recurrent stenotic lesions and to control extravasation from a ruptured vessel that is not controlled by conservative measures. Overall, endovascular thrombectomy is the preferred modality of treatment for the thrombosed dialysis vascular conduits.

Peritoneal Dialysis Catheter Placement: Percutaneous and Peritoneoscopic Techniques.

Chronic peritoneal dialysis (PD) is an underutilized renal replacement therapy in treating end-stage renal disease that has several advantages over hemodialysis. The success of continuous ambulatory PD is largely dependent on a functional long-term access to the peritoneal cavity. Several methods have been developed to place the PD catheter using both surgical and percutaneous techniques. The purpose of this article is to describe the percutaneous techniques using fluoroscopy guidance and peritoneoscope method. While fluoroscopic method uses fluoroscopy guidance and a guidewire to place the PD catheter, the peritoneoscopic technique utilizes a needlescope to directly visualize the peritoneal space to avoid adhesions and omentum during catheter placement. These percutaneous approaches are minimally invasive procedures that can be performed on an outpatient basis without the need for general anesthesia.